“Inherent” and “treated” are two terms that are used a lot in the flame-resistant (FR) fabric world but are sometimes not totally understood by the users of FR garments.

What is an Inherent FR Fabric?

The term ‘inherently flame-resistant fabric’ is one that is used for fabrics that do not require the addition of flame-retardant chemicals after the yarns have been spun or the fabric has been woven or knitted. The yarns for these fabrics use only fibers that are naturally flame resistant; or a blend of fibers that can include a combination of FR fibers or both FR fibers and non-FR fibers. The common theme is no flame retardant chemicals are added to the yarn or fabric.

What is a Treated FR Fabric?

Unlike inherent fabrics, FR treated fabrics have the flame retardant chemicals added to the fabric after it has been woven or knitted.

What is the Difference?

As long as the FR property of the fabric is guaranteed for the useful life of the garment, the key differences are the actual fabric performance numbers. They all have varying arc ratings, different flash fire performance numbers, fabric weights, durability, colorfastness and comfort characteristics – so it is up to the end user to determine which fabric is best suited for their application.

Inherent fabrics do tend to have less susceptibility to issues with improper laundering, but if the garment laundering instructions are followed, there are generally no issues with either type of fabric.

Summary

Inherent fabrics have the FR properties built into the fibers while the treated fabrics have them added after they are woven or knitted. Both have good protection properties and the common name brands with experience in the field can be trusted to perform. Look for the properties you need for your application and find a trusted garment manufacturer to supply you garments of choice.